1. Field of the Invention
The present invention relates to an ATM (asynchronous transfer mode) switching system.
2. Description of the Related Art
In an ATM system constituting a major technique of a B-ISDN (Broadband-Integrated Services Digital Network), data is transferred using an ATM cell.
The ATM cell is transferred not via a software process, but via only a hardware such as an ATM switching system. This is because a large amount of data is transferred at high speed.
On the other hand, for instance, a telephone charging system is established by calculating charging data based on call connecting time, whereas an ATM charging system is established by calculating charging data based on the quantity of transferred ATM cells.
Then, an ATM switching system frequently must acquire data required for a charging process when the charging process is carried out, since ATM cells are transferred at high speed. This may cause a communication amount within the ATM switching system to be increased. As a result, the increase in the communication amount would impede other functions of the ATM switching system and therefore would lower the reliability of ATM switching system.
On the other hand, in another ATM switching system for performing a charging process, if this ATM switching system does not frequently acquire the data necessary for the charging process, then such a memory for temporarily storing the data required for the charging process must be employed. No clear indication how to employ such a memory has been so far made.